Document

S2 Task Force Status
(String test definition)
Tom Himel
5Feb07 Beijing GDE meeting
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Contents
• Review of previous progress presented in
Valencia
• New progress and further conclusions
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Members
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Hasan Padamsee (Co-Chair)
Tom Himel (Co-Chair)
Bob Kephart
Chris Adolphsen
Hitoshi Hayano
Nobu Toge
Hans Weise
Consultants: Sergei Nagaitsev, Nikolai Solyak,
Lutz Lilje, Marc Ross, Daniel Schulte
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Review of Valencia report
• Task force set up by the Global R&D board
– What are the reasons and goals of a system test? Start
with TRC R2 list.
– Determine how many RF units are needed as a system
test before ILC construction
– Do they need to be in a string?
– Is beam needed?
• Had reached preliminary conclusions by Valencia
meeting
mid
• Expected final report in early January 2007
• Wiki page available off the linearcollider.org website
via the Global R&D board wiki or at:
http://www.linearcollider.org/wiki/doku.php?id=rdb:rdb_external:rdb_s2_home
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Preliminary conclusions at Valencia
• The minimum size system test needed to confirm the
performance of a new design is a single RF unit with
ILC like beam. As many tests are statistical in nature,
a longer string test with several RF units or multiple
tests with one RF unit would be better.
• As construction of the project starts, a larger second
phase system test will be needed to check the final
manufactured components. One of the possible
scenarios is to build a test linac with contributions of
a total of several RF units from the three regional
teams of the final consolidated ILC linac system
design. It is S2’s intention to make recommendations
on the suitable scale of this effort by the time of its
final report. Not
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Progress
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Full first draft of report was completed Jan 18, 2007.
Went to R&D board and got approval on Jan 26. Sent to the EC on Jan 26.
We chose to be non-exact in specifying the size of phase 2:
As construction of the project starts, a test facility (or facilities) will be
needed to qualify manufactured RF unit components of the final
consolidated ILC linac system design. These components may be built at
industries in different regions. One of the possible scenarios is to build a
test string with contributions of a total of several RF units from the three
regional teams. There are many factors that will influence the choice
of the size of the string and whether the goals can be accomplished
instead through several smaller tests or one long string. These
factors will be coupled to the future industrialization strategy adopted
for ILC main linac components. Therefore we cannot at this stage
determine the ideal scale of this second phase of system tests.
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Another way to estimate phase 2 size
• Assume that the probability of a failure occurring in a cryomodule is
distributed as 1/time, so the probabilities of a failure occurring between
1 day and 20 days, between 20 days and a year, and between a year
and 20 years are roughly equal. This corresponds to the leading edge
of the bathtub curve (infant mortality) and ignores the trailing edge
caused by items wearing out and the flat bottom of the curve due to
steady-state failures.
• Before construction begins, assume we want to show that less than
10% of the cryomodules that survive the first day will fail in 20 years.
Thus we would tolerate roughly 3% failures in each of the three times
periods noted above.
• To show that the failure rate will not exceed 3% in each of these
periods, we would need to test roughly 30 cryomodules for 20 days or
15 cryomodules for a year. The latter is more reasonable, that is,
under these assumptions the phase 2 test would be the operation of 5
RF units for a year.
• While this model is very crude and has questionable assumptions, it
probably does set the right scale for the size of a phase 2 system test.
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Incredibly rough Phase 1 cost estimate
per system test
Phase
1
nCM
nRF
CM cost
(M$)
RF cost
(M$)
Basic
Cost Sum
Infrastruc
(M$)
. cost
(M$)
1
1
2
3
12
17
1.1
2
0
4
0
0
4
1.2
3
0
6
0
0
6
1.3
3
1
6
3
0
9
Subtotal
9
2
18
6
12
36
Non-beam related facilities
15
Beam related facilities
35
Total
9
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18
6
12
86
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Next steps
• We are virtually done
• Studies of industrialization aspects will need
to be started in earnest. Test facilities
associated with industrialization will also need
to be defined. The RDB has already
discussed extending the S2 task force to
examine these issues.
• No good deed goes unpunished.
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